Common mode noise describes the type of noise that is conducted on all lines in the same direction. To suppress common mode noise, common mode filters or chokes can be installed on conducting lines where common mode noise is present. Traditionally, a common mode filter is comprised of components including an iron core and two coils wound around the iron core with the same winding number. When a common mode current flows through the common mode filter, the two coils generate a magnetic flux in the same direction such that the common mode filter exhibits high impedance and can suppress common mode noise.
Currently, various types of common mode filters apply to low frequency bands. As the market gradually increases and becomes mature, traditional common mode filters will no longer be satisfactory for matching the frequency range of frequency band applications. As the trend of electronic products is geared toward being lighter, thinner, shorter, and smaller, the development of common mode filters that operate in high frequency has also become necessary. In response to the demand for portable electronic products, chip-type common mode filters have been developed.
However, the impedance of conventional common mode filters may oscillate greatly when operating in various frequencies. The conventional common mode filters have less efficiency to suppress common mode noise and may not apply to the high-speed differential transmission signal of USB 3.0, IEEE 1394, LVDS, DVI, HDMI, and MIPI.
This “Discussion of the Background” section is provided for background information only. The statements in this “Discussion of the Background” are not an admission that the subject matter disclosed in this “Discussion of the Background” section constitutes prior art to the present disclosure, and no part of this “Discussion of the Background” section may be used as an admission that any part of this application, including this “Discussion of the Background” section, constitutes prior art to the present disclosure.